MsExchange Blog Spot Telnet25

January 30, 2011

WHITE SPACE EXCHANGE 2010, Where did 1221 Go?

Filed under: General — telnet25 @ 4:38 am

One of important Exchange Server application task & process always been the white space and how we deal with it as Exchange administrator. White space always been one of the most asked, case & specific area in Exchange Server. If you remember in previous versions of Exchange event log 1221 would be logged on the application logs and we would sum these up to find out the total white space in Exchange databases.


Now, as far as basic goes , dealing with Exchange white space always been simple. We don’t take database "off line" and try to run defrag on it, we simply create new DB and move Mail Boxes into newly created DB. Once we are done moving all mail boxes, we would delete the DB has the white space.

The big reason we would do this would be backup considerations, as we would not want to backup white space , otherwise Exchange always been smart enough to find the white space each night after online maintenance and mark the white space as "re-usable" area for the related DB.

Now in Exchange 2010 there are no more 1221 event logs, because Exchange 2010 is dealing with white space in bit more advance approach. Background database maintenance and 24/7 online defragmentation process is explained in details as fallows.

If you like to see the available space on the database you can run fallowing

Get-MailboxDatabase Database1 -Status | FL AvailableNewMailboxSpace

Database White Space

The database size on the physical disk isn’t just the number of users multiplied by the mailbox storage quota. When the majority of users aren’t approaching their mailbox storage quota, the databases consume less space and white space isn’t a capacity concern. The database itself will always have free pages, or white space, spread throughout. During background database maintenance, items marked for removal from the database are removed, which frees these pages. The percentage of white space is constantly changing due to the efforts of the 24×7 online defragmentation process.

You can estimate the amount of white space in the database by knowing the amount of mail sent and received by the users with mailboxes in the database. For example, if you have 100 2-GB mailboxes (total of 200 GB) in a database where users send and receive an average of 10 MB of mail per day, the amount of white space is approximately 1 GB (100 mailboxes × 10 MB per mailbox). The amount of white space can exceed this approximation if background database maintenance isn’t able to complete a full pass.

Click here to read more

Oz Casey, Dedeal
MCSE 2003, M+, S+, MCDST
Security+, Project +, Server + (Blog (Blog)


January 18, 2011

Smtp; 5.1.0 – Unknown address error 550-‘5.7.1 Command rejected’ (

Filed under: General — telnet25 @ 5:35 pm

Issue : Sending mail to specific recipient is failing with  SMTP XXX code.

Solution:  fallow the steps below

Delivery has failed to these recipients or distribution lists:

An error occurred while trying to deliver this message to the recipient’s e-mail address. Microsoft Exchange will not try to redeliver this message for you. Please try resending this message, or provide the following diagnostic text to your system administrator.

The following organization rejected your message: [].

Diagnostic information for administrators:

Generating server:

[] #<[] #5.0.0 smtp; 5.1.0 – Unknown address error 550-‘5.7.1 Command rejected’ (delivery attempts: 0)> #SMTP#

More Explanation

If you get a ticket from your helpdesk or you are the Tier 1 person and have no idea what to do, keep reading as I will talk about very basic how to troubleshoot such issues.

Now let’s quickly understand couple basic mail flow principles. When sending mail, the sending server attempts to try to locate the mail, in reality it is up to receiver weather to receive such e-mail or not. Furthermore the recipient mail server could be generating whatever error code for it wants for whatever reason it has.

Forget about mail servers and now think about a postman, who works at the neighborhood post office. He loads his truck with bunch of mails and start delivering them, if you do not have dedicated post box in front of your home he drops the envelope in there. It is up to you whether you pick them up or not in this example.

Same post man might have another packet for you this time he won’t drop into mailbox in front of your home, he knocks on your door and, tries to get signature from you. Let’s suppose you open the door, postman told you, sir I have package for you, please sign the computer before I give it to you.

Now it is up to you to tell the post man, I don’t care about this package, I won’t sign anything just take this back? ( this is perfectly possible ) in this case post man will take the package and write note on it most likely say something like rejected by blah blah , 550-‘5.7.1

Steps to Understand what went wrong

  • Now to investigate such issues the easiest thing to do go here
  • In here you will perform Inbound SMTP test
  • Put the destination recipient mail address here


Now you can see the reason why your mail server could not deliver the message, in reality no mail will route to this address as the recipient mail servers does have errors indicated in below picture


So now how you are going to fix this?

You really cannot fix this as you are not generating the errors ( your mail server) nor you are the administrator of recipient mail servers. I guess you can locate the technical support people for the destination SMTP address space and open ticket or talk to someone , saying, hey we have been trying to sent you guys mail your mail server is keep rejecting it , can someone fix these problems or tell us when you will accept mail.


The point I wanted to make is to lead some of you to develop troubleshooting skill and  process and stick to it. Many of errors in such easily can be identified by using online tools, Telnet from command line into port 25 to destination mail server or any other way.

Oz Casey, Dedeal
MCSE 2003, M+, S+, MCDST
Security+, Project +, Server + (Blog (Blog)

January 13, 2011

Exchange 2010 is Best Mail Server

Filed under: General — telnet25 @ 6:54 pm

If you have not seen the recent post on MS Exchange website please take a moment as check it out. Exchange 2010 is for sure is the best messaging application and made significant changes in messaging business…..



First look: Exchange 2010 beta shines

Microsoft Exchange 2010

continues Redmond’s longstanding market leadership in mail servers and related software. This release shows why the company’s once-reviled product continues to be deployed widely in enterprises: it works, it scales, and it continues to gain important new features. In our tests, we saw improved management, administration, and reliability features plus an enhanced experience for users that includes automatic transcription of voicemails, delivery reports for messages, and extensive self-service options. Although light on wholesale changes and heavy on refinements, Exchange 2010 is nevertheless a major step up from Exchange 2007.

Oz Casey, Dedeal
MCSE 2003, M+, S+, MCDST
Security+, Project +, Server + (Blog (Blog)

January 4, 2011

Exchange 2010 Design Questions & Some Useful Links……

Filed under: General — telnet25 @ 4:37 pm

One of the most frequent asked question is how to locate resources if Exchange 2010 migration is on the way. If you do not have previous experience and wish to go for migration you may want to check fallowing resources before and during migration.In general migration process is much simpler if I have to compare the previous migration scenarios, I need to admit going from E03 to E210 or E07 to E210 is fairly simple. The question is what hardware to purchase? your scenario might be or will be different, if you are purchasing new HW , talk to Vendor to see their best practice papers they normally do have established baseline which may make your job easy.

The future of Exchange product line seems to be “Online” hosted services, only reason I say this is the key factor “Cost”. MS seems to be very push when it comes to MS hosted platform, I have seen MB prices goes down to couple bucks with adequate & reasonable price. After all it could make more sense to go to Cloud. This of course is not cast into stone as I said every one will have different scenario needs etc.

Whatever your scenario, below links may help you going forward and good luck on your migration.


And always check out Exchange Team blog.


Oz Casey, Dedeal

Blog at